Construction of eccentrics in connecting rod drives for internal combustion engines with overhead camshaft



2,900,838 CESROD DRIVES 5, 1959 A. RODER CONSTRUCTION OF ECCENTRICS IN CONNECTIN FOR INTERNAL COMBUSTION ENGIN WITH OVERHEAD CAMSHAFT Filed Nov. 26, 1956 PERIPHERY EMBRA G United States Patent CQNSTRUCTION OF ECCENTRICS IN CONNECT- ING R01!) DRIVES FOR INTERNAL COMBUS- TION ENGINES WITH OVERHEAD CAMSHAFT Albert Roder, Heilbronn, Germany, assignor to NSU Werke A.G., Neckarsulm, Wurtemburg, Germany Application November 26, 1956, Serial No. 624,320

Claims priority, application Germany November 28, 1955 3 Claims. (Cl. 74-570) The present invention relates to improvements in an eccentric construction for use in operably connecting crank drive means associated with an internal combustion engine drive shaft with an overhead cam shaft.

To reduce mechanical noise in high-speed internal cornbustion engines, more particularly for vehicles, drives by means of connecting rods and eccentrics have recently been introduced for the overhead camshafts.

As the need is for further reduction of noise, it would be expedient if possible, when using such connecting rod drives, to restrict the bearing plays, which may cause rattle noises, to a still greater extent than hitherto during operation. This means that the manufacturing accuracies of the two pairs of eccentrics required must be still further increased.

In the type of construction of such eccentric pairs known hitherto, they are in one piece. In this regard attention is called to my prior application Serial Numher 321,670 filed November 20, 1952, and now Patent No. 2,779,321, dated January 29, 1957. The machining must therefore be carried out with auxiliary devices which are provided with the necessary machining centres and do not sufliciently avoid certain inaccuracies.

The invention consists in an eccentric construction, which provides a separate eccentric disc for each eccentric. Each disc is accommodated by one device during manufacture. As the fixing on this device can be done very accurately, the individual eccentric discs can be made in much better manufacturing quality. In view of the fact that all the discs can be manufactured on the same device, when they are combined to form eccentric pairs their exactitude is superior to the type of construction in one piece known hitherto. In addition there is the further advantage of corresponding reduction in cost, because the eccentric discs can be sliced from circular rods by automatic machines, and need not be made as forged pieces as in the former method of manufacture.

A further feature contributing to the reduction in cost is that the starting material is carburized before the machining in order to obtain, by subsequent chilling, hard bearing surfaces on the slide face of the eccentrics, and nevertheless have a core available for finishing the alignment bores after the hardening. This makes it possible to dispense with the trimming away of the case-hardened layer after carburizing, which was necessary hitherto. The eccentrics on the control shaft which runs at half speed in 4-stroke motors and a similar eccentric pair which is mounted on the overhead camshaft, are fixed on one hand by the shaft carrying them and on the other by an eccentrically arranged alignment pin. Such a general arrangement is shown in my aforementioned application. The positive connection against rotation can be effected either by this alignment pin, which can be correspondice 1eccentric disc 2--shaft 3-driving pin 4fixing pin 5--bore 6--bore for lightening The eccentric pairs are formed by two separately machined eccentric discs in the following manner: the eccentrics 1 are arranged on the shaft 2 passing through the bore '5 and are fixed by at least one parallel pin connection 4. A further pin 3 projects laterally beyond the eccentrics 1 and serves as a drive connection to the driving wheel or the camshaft.

A further feature of the invention is the manufacture of the eccentrics 1 from circular material carburized on its convex surface. This has the advantage that the slide faces 7 of the eccentrics 1 can be hardened and at the same time ensures good machinability at the remaining places. According to requirements, the eccentrics 1 may be constructed in parallel or reverse image. To make them lighter, each eccentric 1 is provided with a bore 6.

I claim:

1. An eccentric construction for use in operably connecting crank drive means associated with an internal combustion engine drive shaft with an overhead cam shaft, comprising two disc components, each disc component having an eccentric bore for receiving the cam shaft, each disc component being provided with at least one further bore, and pin means lodged in said further bores after the disc components have been placed in facial contact in reverse image on the cam shaft to maintain the disc components in such assembled relationship, with the crank drive means being adapted to embrace the periphery of each disc component.

2. An eccentric construction as claimed in claim 1 in which each disc component is provided with another bore and further pin means being arranged in said another bores, with the length of the further pin means being such that at least one end thereof projects beyond the outer face of one of the disc components for serving as a drive connection to the engine drive shaft or the cam shaft.

3. An eccentric construction as claimed in claim 1 in which the length of said pin means, is such that at least one end thereof projects beyond the outer face of one of the disc components for serving as a drive connection to the engine drive shaft or the cam shaft.

References Cited in the file of this patent UNITED STATES PATENTS 299,731 Brotherhood June 3, 1884 662,015 Noyes Nov. 20, 1900 792,281 Norling June 13, 1905 2,799,321 Roder Ian. 29, 1957 2,817,248 Motzet et a1 Dec. 24, 1957 FOREIGN PATENTS 355,597 France Sept. 2, 1905 881,284 Germany June 29, 1953 

